Multifunctional reactive inks, methods of use and manufacture thereof

ABSTRACT

In one embodiment, a method includes dispersing a plurality of particles in solution to form a dispersion and adding a stabilizing agent to the dispersion in an amount sufficient to cause the dispersion to exhibit one or more predetermined rheological properties. The particles in the dispersion are configured to complete a self-propagating and/or self-sustaining reaction upon initiation thereof. In another embodiment, a method includes depositing a material on a substrate. The material includes: a plurality of particles configured to complete a self-propagating and/or self-sustaining reaction upon initiation thereof, a solvent system, and one or more stabilizing agents.

The United States Government has rights in this invention pursuant toContract No. DE-AC52-07NA27344 between the United States Department ofEnergy and Lawrence Livermore National Security, LLC for the operationof Lawrence Livermore National Laboratory.

FIELD OF THE INVENTION

The present invention relates to three-dimensional (3D) printing andfabrication, and more particularly to 3D printing and fabrication usingextrusion techniques and ink compositions capable of completing aself-propagating and/or self-sustaining reaction upon initiationthereof.

BACKGROUND

3D printing is an emerging field within the modern manufacturingindustry. The technology has garnered serious attention, and commercialentities are even opening access to 3D printing hardware for public useto manufacture custom goods. While the technique is revolutionary, thereremains much development and opportunity for improving and expanding theapplication of the technique across a broader range of applications.

A major obstacle to diversifying the applicability of 3D printingtechniques, and particularly extrusion-based printing techniques, islimitations on available materials suitable for use with the technique.Conventional extrusion-based 3D printing techniques utilizepolymer-based materials such as polycarbonate (PC) and/or acrylonitrilebutadiene styrene (ABS). The material is typically filamentous in form,and is fed toward and through a heated nozzle, which melts the materialand deposits a melted “bead” on a substrate.

This configuration and technique is limiting. There is no suitable usein extruding liquid-based materials (e.g. slurries, suspensions,solutions, etc.) into arbitrary 3D dimensions because such materialslack strength and will flow too freely upon extrusion. Further, theapplication of heat to the material at the nozzle precludes usingconventional extrusion techniques with energetic materials, such asreactive inks comprising thermite constituents (or any otherconstituents tending to generate an undesirable reaction or prematurelyinitiate a desired reaction upon the nozzle applying heat).

Accordingly, it would be beneficial to provide systems, methods, andmaterials expanding the applicability of conventional 3D printingtechniques to new materials such as reactive inks. It would be furtherbeneficial to determine additional techniques for using such reactiveinks in new applications such as custom repair and modification ofexisting materials in nearly any environment, use of reactive inks toprovide localized heating to a target, and synthesis of new materialsand/or systems using reactive inks.

SUMMARY

In one embodiment, a method includes dispersing a plurality of particlesin solution to form a dispersion and adding a stabilizing agent to thedispersion in an amount sufficient to cause the dispersion to exhibitone or more predetermined rheological properties; the particles in thedispersion are configured to complete a self-propagating and/orself-sustaining reaction upon initiation thereof.

In another embodiment, a method includes depositing a material on asubstrate; the material includes a plurality of particles configured tocomplete a self-propagating and/or self-sustaining reaction uponinitiation thereof, a solvent system and one or more stabilizing agents.

Other aspects and advantages of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts a reactive ink composition prior toextrusion and deposition on a substrate, according to one embodiment.

FIG. 2 is a simplified schematic of a 3D printing apparatus, accordingto one embodiment.

FIG. 3A is a simplified schematic of a damaged substrate, according toone embodiment.

FIG. 3B is a schematic representation of a repaired substrate, accordingto one embodiment.

FIG. 4A depicts a schematic representation of a multi-layer structurecustom-fabricated using reactive ink, according to one embodiment.

FIG. 4B depicts a schematic representation of a monolithic structurecustom-fabricated using reactive ink, according to one embodiment.

FIG. 5 shows a schematic representation of a structure custom-fabricatedusing reactive ink, according to one embodiment.

FIG. 6 is a flowchart of a method, according to one embodiment.

FIG. 7 is a flowchart of a method, according to one embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofhigh-surface area catalysts having high activity and thermal stabilityover a broad temperature range and/or methods of making the same.

In one general embodiment, a material includes a plurality of particles,a solvent system and one or more stabilizing agents; the particles areconfigured to complete a self-propagating and/or self-sustainingreaction upon initiation thereof.

In another general embodiment, a method includes dispersing a pluralityof particles in solution to form a dispersion and adding a stabilizingagent to the dispersion in an amount sufficient to cause the dispersionto exhibit one or more predetermined rheological properties; theparticles in the dispersion are configured to complete aself-propagating and/or self-sustaining reaction upon initiationthereof.

In still another general embodiment, a method includes depositing amaterial on a substrate; the material includes a plurality of particlesconfigured to complete a self-propagating and/or self-sustainingreaction upon initiation thereof, a solvent system and one or morestabilizing agents.

As understood herein, a “reactive ink” is a formulation of two or moredifferent constituents, which, upon initiation, carries aself-propagating and/or self-sustaining reaction to completion.

A reactive ink, as disclosed herein and as compared to liquid-basedmaterials such as slurries, suspensions, solutions, etc., is designed tohave internally-provided structural strength, such that the ink retainsits filamentary geometry upon extrusion. In various embodiments, thepresently described inks can therefore support their own weight and beprinted into three-dimensional objects, and also can span lengths tosome distance without additional structural support being provided tothe printed ink.

Moreover, in some embodiments the reactive ink may comprise constituentsfor a thermite or intermetallic reaction. Upon reaction, thermite orintermetallic composites undergo high-temperature reactions and yield aproduct phase in-place. A reactive ink could thus be printed onto asubstrate, or into an arbitrary volume, and then reacted. The reactionwould serve as a localized source to provide controlled heating toadjacent material. Furthermore, a product phase will form in-place ofthe printed material, and can be used to restore some functionality to apart (i.e. strength, electrical conductivity, thermal barrier). Due tothe high reaction temperatures, little to no thermal post-processingwith external heat sources will be required. Since the thermal stressesduring the reaction will be a direct function of the reactionexothermicity as well as the printed feature size, a user will havecontrol over the temperature history in the sample. This providesadditional advantages over traditional techniques such as welding, inwhich a much larger volume of material is subjected to heating and theresultant thermal stresses. Unlike welding, a reactive ink is evencompatible with temperature-sensitive materials, due to the fact thatthe user controls the energy deposition by controlling the formulationand feature sizes.

Moreover still, since a reactive ink can be delivered to a targetfluidically, it is possible to use this technique in harmful orunreachable situations (e.g. to directly synthesize and/or repair partsof the International Space Station, satellites, deep-sea pipelinesand/or equipment, etc.). Delivery of the ink can occur via a host oftechniques including, but not limited to, a hand-held syringe, acaulking gun, a 3D printing apparatus with precision positioningcapabilities, or a programmable robotic arm. The delivery method willdepend on the particular application, and what feature resolution andamount of material is needed.

Preferably, the reactive inks disclosed herein are deliverable viafluidic systems as simple as a syringe and as complex as modern 3Dprinting apparatuses. Accordingly, reactive inks disclosed hereincomprise at least one liquid or flowable component to enable fluidicdelivery of the reactive ink.

More preferably, upon completing the self-propagating and/orself-sustaining reaction, the reactive inks discussed herein form afully functional composite material or product. In other words, thestructure formed from reacting the reactive ink is either fullyfunctional in a capacity filled by the substrate onto which the ink wasprinted before incurring damage, or the structure formed from reactingthe reactive ink is fully functional in a capacity for which it wasdesigned. The former is usually the case for embodiments describedherein having to do with repairing existing materials, while the latteris usually the case for materials formed from reactive inks usingreactive additive manufacturing.

Reactive Ink Formulation

Turning now to the Figures, FIG. 1 depicts an exemplary schematic of asystem 100 having a reactive ink formulation prior toprinting/extrusion/deposition, according to one embodiment within thescope of the present inventive concepts. As shown in FIG. 1, thereactive ink is in a container 102, and comprises a plurality ofparticles 106, 108 dispersed in a solvent system 104 with one or morestabilizing agents 110. The plurality of particles 106, 108 preferablyincludes particles of at least two different types, creating abinary-order (or higher, e.g. tertiary, quaternary, etc.) reactivesystem of particles 106, 108 capable of carrying a self-propagatingand/or self-sustaining reaction to completion upon initiation thereof.

While in some embodiments it may be sufficient to use a binary-orderreactive system, for example to repair a damaged substrate, in variousembodiments the presently disclosed multifunctional reactive inks mayinclude higher-order reactive systems designed to simultaneously confermultiple functional properties and/or physical characteristics uponcompletion of the self-propagating and/or self-sustaining reaction.

In preferred approaches, the particles comprise anywhere from about 30vol % to about 80 vol % of the multifunctional reactive ink formulation;in more preferred approaches, from about 40 vol % to about 60 vol % ofthe multifunctional reactive ink formulation; and in particularlypreferred approaches, from about 45 vol % to about 55 vol % of themultifunctional reactive ink formulation.

For example, the particles may include at least two different precursormaterials for forming a glass, an alloy, a ceramic, a cermet, etc., aswould be understood by one having ordinary skill in the art upon readingthe present descriptions. The precursor materials may be configuredand/or arranged in the reactive ink so as to form the correspondingfinal material upon initiation of, during propagation of, and/or uponcompletion of a self-propagating and/or self-sustaining reaction. Theparticles are preferably configured to carry such reaction to completionupon initiation thereof.

In more exotic formulations, particles may be disposed in a liquid metalof a type different than the particles, and preferably the combinationof the particles and the liquid metal are configured to carry aself-propagating and/or self-sustaining reaction to completion. Morespecifically, the particles may be disposed throughout a liquid matrix,in one approach.

In still more embodiments, instead of, or in addition to particlesdesigned to carry a self-propagating reaction to completion, amultifunctional reactive ink formulation may include multiple molecularprecursors of a reactive material.

In various approaches, the plurality of particles may include anycombination of particle types which, upon initiation, can support aself-propagating and/or self-sustaining reaction. A partial list ofcombustible or reactive binary composite materials is shown in Table 1.In some formulations, ternary (or greater) mixtures can be utilized tospecifically tailor the rate of energy release, as well as theproperties of the reacted product, among any equivalent thereof thatwould be known to one having ordinary skill in the art upon reading thepresent descriptions. Of course, the plurality of particles may alsoinclude any number of combinations listed in Table 1, in moreapproaches. Those having ordinary skill in the art will appreciate thereaction schema listed in Table 1 to be stoichiometric formulae, suchthat the integer values appearing before the various constituentmaterials listed refer to a stoichiometric ratio of the respectiveconstituents in the corresponding reaction. Thus, the first reactionlisted in Table 1 could be rewritten as “2Al+3AgO.” There are severalother parameters, not captured in Table 1, which are well known toaffect the reactivity within a given composition, and will also affectthe characteristics of the product. Some examples include particle size,particle morphology, equivalence ratio, density, or any others whichwould be known to those having ordinary skill in the art of reactivematerials.

In particularly preferred embodiments, the particles comprise either: acombination of aluminum and nickel (Al+Ni), a combination of titaniumand nickel (Ti+Ni), a combination of boron carbide and titanium(B₄C+Ti), or any combination thereof, e.g. [(Al+Ni), ±(Ti+Ni),±(B₄C+Ti)].

TABLE 1 Exemplary Self-Propagating and/or Self-Sustaining ReactionsConstituents Reaction Type 2Al 3AgO Thermite Reaction 2Al 3Ag₂O ThermiteReaction 2Al Bi₂O₃ Thermite Reaction 2Al 3CoO Thermite Reaction 8Al3Co₃O₄ Thermite Reaction 2Al Cr₂O₃ Thermite Reaction 2Al 3CuO ThermiteReaction 2Al 3Cu₂O Thermite Reaction 2Al Fe₂O₃ Thermite Reaction 8Al3Fe₃O₄ Thermite Reaction 2Al 3HgO Thermite Reaction 10Al 3I₂O₅ ThermiteReaction 4Al 3MnO₂ Thermite Reaction 2Al MoO₃ Thermite Reaction 10Al3Nb₂O₅ Thermite Reaction 2Al 3NiO Thermite Reaction 2Al Ni₂O₃ ThermiteReaction 2Al 3PbO Thermite Reaction 4Al 3PbO₂ Thermite Reaction 8Al3Pb₃O₄ Thermite Reaction 2Al 3PdO Thermite Reaction 4Al 3SiO₂ ThermiteReaction 2Al 3SnO Thermite Reaction 4Al 3SnO₂ Thermite Reaction 10Al3Ta₂O₂ Thermite Reaction 4Al 3TiO₂ Thermite Reaction 16Al 3U₃O₈ ThermiteReaction 10Al 3V₂O₅ Thermite Reaction 4Al 3WO₂ Thermite Reaction 2Al WO₃Thermite Reaction 2B Cr₂O₃ Thermite Reaction 2B 3CuO Thermite Reaction2B Fe₂O₃ Thermite Reaction 8B 3Fe₃O₄ Thermite Reaction 4B 3MnO₂ ThermiteReaction 8B 3Pb₃O₄ Thermite Reaction 3Be B₂O₃ Thermite Reaction 3BeCr₂O₃ Thermite Reaction Be CuO Thermite Reaction 3Be Fe₂O₃ ThermiteReaction 4Be Fe₃O₄ Thermite Reaction 2Be MnO₂ Thermite Reaction 2Be PbO₂Thermite Reaction 4Be Pb₃O₄ Thermite Reaction 2Be SiO₂ Thermite Reaction3Hf 2B₂O₃ Thermite Reaction 3Hf 2Cr₂O₃ Thermite Reaction Hf 2CuOThermite Reaction 3Hf 2Fe₂O₃ Thermite Reaction 2Hf Fe₃O₄ ThermiteReaction Hf MnO₂ Thermite Reaction 2Hf Pb₃O₄ Thermite Reaction Hf SiO₂Thermite Reaction 2La 3AgO Thermite Reaction 2La 3CuO Thermite Reaction2La Fe₂O₃ Thermite Reaction 2La 3HgO Thermite Reaction 10La 3I₂O₅Thermite Reaction 4La 3MnO₂ Thermite Reaction 2La 3PbO Thermite Reaction4La 3PbO₂ Thermite Reaction 8La 3Pb₃O₄ Thermite Reaction 2La 3PdOThermite Reaction 4La 3WO₂ Thermite Reaction 2La WO₃ Thermite Reaction6Li B₂O₃ Thermite Reaction 6Li Cr₂O₃ Thermite Reaction 2Li CuO ThermiteReaction 6Li Fe₂O₃ Thermite Reaction 8Li Fe₃O₄ Thermite Reaction 4LiMnO₂ Thermite Reaction 6Li MoO₃ Thermite Reaction 8Li Pb₃O₄ ThermiteReaction 4Li SiO₂ Thermite Reaction 6Li WO₃ Thermite Reaction 3Mg B₂O₃Thermite Reaction 3Mg Cr₂O₃ Thermite Reaction Mg CuO Thermite Reaction3Mg Fe₂O₃ Thermite Reaction 4Mg Fe₃O₄ Thermite Reaction 2Mg MnO₂Thermite Reaction 4Mg Pb₃O₄ Thermite Reaction 2Mg SiO₂ Thermite Reaction2Nd 3AgO Thermite Reaction 2Nd 3CuO Thermite Reaction 2Nd 3HgO ThermiteReaction 10Nd 3I₂O₅ Thermite Reaction 4Nd 3MnO₂ Thermite Reaction 4Nd3PbO₂ Thermite Reaction 8Nd 3Pb₃O₄ Thermite Reaction 2Nd 3PdO ThermiteReaction 4Nd 3WO₂ Thermite Reaction 2Nd WO₃ Thermite Reaction 2Ta 5AgOThermite Reaction 2Ta 5CuO Thermite Reaction 6Ta 5Fe₂O₃ ThermiteReaction 2Ta 5HgO Thermite Reaction 2Ta I₂O₅ Thermite Reaction 2Ta 5PbOThermite Reaction 4Ta 5PbO₂ Thermite Reaction 8Ta 5Pb₃O₄ ThermiteReaction 2Ta 5PdO Thermite Reaction 4Ta 5WO₂ Thermite Reaction 6Ta 5WO₃Thermite Reaction 3Th 2B₂O₃ Thermite Reaction 3Th 2Cr₂O₃ ThermiteReaction Th 2CuO Thermite Reaction 3Th 2Fe₂O₃ Thermite Reaction 2ThFe₃O₄ Thermite Reaction Th MnO₂ Thermite Reaction Th PbO₂ ThermiteReaction 2Th Pb₃O₄ Thermite Reaction Th SiO₂ Thermite Reaction 3Ti 2B₂O₃Thermite Reaction 3Ti 2Cr₂O₃ Thermite Reaction Ti 2CuO Thermite Reaction3Ti 2Fe₂O₃ Thermite Reaction Ti Fe₃O₄ Thermite Reaction Ti MnO₂ ThermiteReaction 2Ti Pb₃O₄ Thermite Reaction Ti SiO₂ Thermite Reaction 2Y 3CuOThermite Reaction 8Y 3Fe₃O₄ Thermite Reaction 10Y 3I₂O₅ ThermiteReaction 4Y 3MnO₂ Thermite Reaction 2Y MoO₃ Thermite Reaction 2Y Ni₂O₃Thermite Reaction 4Y 3PbO₂ Thermite Reaction 2Y 3PdO Thermite Reaction4Y 3SnO₂ Thermite Reaction 10Y 3Ta₂O₅ Thermite Reaction 10Y 3V₂O₅Thermite Reaction 2Y WO₃ Thermite Reaction 3Zr 2B₂O₃ Thermite Reaction3Zr 2Cr₂O₃ Thermite Reaction Zr 2CuO Thermite Reaction 3Zr 2Fe₂O₃Thermite Reaction 2Zr Fe₃O₄ Thermite Reaction Zr MnO₂ Thermite Reaction2Zr Pb₃O₄ Thermite Reaction Zr SiO₂ Thermite Reaction Al 2BIntermetallic Reaction 4Al 3C Intermetallic Reaction 2Al CaIntermetallic Reaction 4Al Ca Intermetallic Reaction 4Al CeIntermetallic Reaction Al Co Intermetallic Reaction 4Al Co IntermetallicReaction 5Al 2Co Intermetallic Reaction 3Al Cr Intermetallic Reaction AlCu Intermetallic Reaction Al Fe Intermetallic Reaction 3Al FeIntermetallic Reaction 4Al La Intermetallic Reaction Al Li IntermetallicReaction Al Mn Intermetallic Reaction Al Ni Intermetallic Reaction Al3Ni Intermetallic Reaction Al Pd Intermetallic Reaction 4Al PrIntermetallic Reaction Al Pt Intermetallic Reaction 4Al Pu IntermetallicReaction 2Al 3S Intermetallic Reaction Al Ta Intermetallic Reaction 3AlTa Intermetallic Reaction Al Ti Intermetallic Reaction Al 3TiIntermetallic Reaction 2Al Ti Intermetallic Reaction 3Al TiIntermetallic Reaction 3Al 2Ti Intermetallic Reaction 4A1 UIntermetallic Reaction 3A1 V Intermetallic Reaction 2A1 Zr IntermetallicReaction 4B C Intermetallic Reaction 6B Ce Intermetallic Reaction 2B CrIntermetallic Reaction 2B Hf Intermetallic Reaction 6B La IntermetallicReaction 2B Mg Intermetallic Reaction 6B Mg Intermetallic Reaction 2B MnIntermetallic Reaction 2B Mo Intermetallic Reaction 2B Nb IntermetallicReaction 6B Sm Intermetallic Reaction 6B Si Intermetallic Reaction 2B TaIntermetallic Reaction 4B Th Intermetallic Reaction B Ti IntermetallicReaction 2B Ti Intermetallic Reaction 2B U Intermetallic Reaction 4B UIntermetallic Reaction B V Intermetallic Reaction 2B V IntermetallicReaction 5B 2W Intermetallic Reaction 6B Y Intermetallic Reaction 2B ZrIntermetallic Reaction 3Ba 2Bi Intermetallic Reaction Ba 2CIntermetallic Reaction 2Ba Pb Intermetallic Reaction 3Ba 2SbIntermetallic Reaction 2Ba Sn Intermetallic Reaction Be 2C IntermetallicReaction 2Be C Intermetallic Reaction 5Be Nb Intermetallic Reaction 13BePu Intermetallic Reaction 13Be U Intermetallic Reaction Bi KIntermetallic Reaction Bi 3K Intermetallic Reaction Bi Li IntermetallicReaction 2C Ca Intermetallic Reaction 2C Ce Intermetallic Reaction 3C7Cr Intermetallic Reaction C Hif Intermetallic Reaction 2C LaIntermetallic Reaction 3C 7Mn Intermetallic Reaction C 2Mo IntermetallicReaction 2C 2Na Intermetallic Reaction 0.98C Nb Intermetallic Reaction CNb Intermetallic Reaction C 2Nb Intermetallic Reaction C SiIntermetallic Reaction 2C Sr Intermetallic Reaction C Ta IntermetallicReaction 1.94C Th Intermetallic Reaction 2C Th Intermetallic Reaction CTi Intermetallic Reaction C U Intermetallic Reaction 2C U IntermetallicReaction C V Intermetallic Reaction C W Intermetallic Reaction C ZrIntermetallic Reaction Ca 2Mg Intermetallic Reaction 2Ca PbIntermetallic Reaction Ca Si Intermetallic Reaction Ca Sn IntermetallicReaction 2Ca Sn Intermetallic Reaction 11Cd Pu Intermetallic Reaction CeMg Intermetallic Reaction 2Ce Pb Intermetallic Reaction Ce 2SiIntermetallic Reaction Ce Zn Intermetallic Reaction Co Si IntermetallicReaction Cr Si Intermetallic Reaction Cr 2Si Intermetallic Reaction 3CrSi Intermetallic Reaction 5Cr 3Si Intermetallic Reaction Cu 2MgIntermetallic Reaction 2Cu Mg Intermetallic Reaction Cu Pd IntermetallicReaction Fe Si Intermetallic Reaction Ge 2Mg Intermetallic Reaction 2GeNb Intermetallic Reaction Li Pb Intermetallic Reaction Li SbIntermetallic Reaction Li Sn Intermetallic Reaction Mg S IntermetallicReaction 3Mg 2Sb Intermetallic Reaction Mg Se Intermetallic Reaction 2MgSi Intermetallic Reaction 2Mg Sn Intermetallic Reaction Mg TeIntermetallic Reaction 2Mg Th Intermetallic Reaction Mg U IntermetallicReaction Mg Y Intermetallic Reaction Mn S Intermetallic Reaction Mn SiIntermetallic Reaction Mn 1.7Si Intermetallic Reaction Mo 2SiIntermetallic Reaction Mo 7Si Intermetallic Reaction 3Mo SiIntermetallic Reaction 5Mo 3Si Intermetallic Reaction Na SbIntermetallic Reaction Na Sn Intermetallic Reaction Nb Ni IntermetallicReaction Nb 2Si Intermetallic Reaction 5Nb 3Si Intermetallic Reaction NiSi Intermetallic Reaction Pd Sn Intermetallic Reaction Pu 12ZnIntermetallic Reaction S Zn Intermetallic Reaction Si 2Ta IntermetallicReaction 2Si Ta Intermetallic Reaction 3Si 5Ta Intermetallic Reaction2Si Th Intermetallic Reaction 2Si Ti Intermetallic Reaction 3Si 5TiIntermetallic Reaction 2Si U Intermetallic Reaction 2Si V IntermetallicReaction 2Si W Intermetallic Reaction Si Y Intermetallic Reaction Si 2ZrIntermetallic Reaction 2Si Zr Intermetallic Reaction 3Si 5ZrIntermetallic Reaction 2U 17Zn Intermetallic Reaction 2Zn ZrIntermetallic Reaction

In other embodiments, rather than two types of particles, amultifunctional reactive ink may include one type of particles coatedwith another type of material, for example aluminum particles platedwith nickel, resulting in essentially a core-shell or laminateconfiguration, particles of a composite and/or alloyed material, etc. aswould be understood by those having ordinary skill in the art uponreading the present descriptions.

In various embodiments, the particles may be characterized by an averageparticle diameter in a range from about 0.01 microns to about 100microns. Small particle size is advantageous to facilitating aself-propagating and/or self-sustaining reaction and a relatively fastreaction rate, because particles may be more homogenously dispersedthroughout the multifunctional reactive ink and further due at least inpart to a relatively reactive higher surface area throughout themultifunctional reactive ink. Particle size will also have an impact onthe effective heating and/or cooling rate, which may result in differentgrain sizes of the product, or may result in other features which canimpact the properties of the product.

Turning now to the solvent system 104, in preferred embodiments thesolvent system comprises solvents having a low viscosity and ahigh-to-moderate boiling point (e.g. in a range from about 50 to about100 degrees)° C. to facilitate quick, efficient, facile evaporationthereof during and/or after depositing the multifunctional reactive inkon a substrate. In particularly preferred embodiments, the solventsystem 104, optionally in conjunction with the stabilizer(s) 110, ispresent in an effective amount such that the material is structurallyself-supporting during deposition. For example, the material could bedeposited vertically onto itself to form a substantially rod-likestructure that would not collapse or deform significantly under its ownweight. Of course, in various embodiments the material could bedeposited so as to generate a three-dimensional structure in nearly anyconfiguration.

In more embodiments, the solvent system may optionally include one ormore relatively higher volatility solvents than those describedimmediately above. For example, in one approach employing gradedvolatility solvent systems reduces the drying rate and/or stressesassociated with drying, which in turn helps reduce cracking and/or otherdeformities, artifacts, inclusions, etc. in the deposited/extrudedreactive ink formulation. In such approaches, the solvent system mayinclude one or more solvents characterized by a boiling point up toabout 250° C.

In still more embodiments, the solvent system 104 is preferablyconfigured to leave negligible amounts organic residue in the materialafter evaporation.

With continuing reference to FIG. 1, and turning now to the stabilizingagents 110, in preferred embodiments the one or more stabilizing agentsare configured to prevent the particles from forming aggregates prior tocompleting the self-propagating and/or self-sustaining reaction. Asdiscussed in further detail below, particularly with reference to FIG.6, some or all particles 106, 108 suitable for use in the presentlydisclosed multifunctional reactive inks have a tendency to formaggregates in suspension due to weak interactions such as hydrogen bondsor Van der Waals forces. Aggregation is disadvantageous because it mayinterfere with extrusion (larger particles are more difficult to extrudeconsistently without blockage) and/or reaction propagation (due toinaccessibility of reaction components to other reaction components,undesirable stoichiometric ratio of accessible reaction components,etc.). Accordingly, it is advantageous to disperse particles and breakup any aggregates in the multifunctional reactive ink formulation.

However, simply dispersing the particles is insufficient due to tendencyto reform the aggregates. Accordingly, it is advantageous to include oneor more stabilizing agents to prevent the particles from formingaggregates while in the ink. As discussed herein, “preventing” the(re)formation of aggregates should be understood to include generallyexerting a degree of control over particles' natural tendency to formaggregates. “Preventing” the (re)formation of aggregates need notnecessarily prevent the formation of any aggregates whatsoever, but mayalso include altering (e.g. substantially limiting or decreasing)particles' natural tendency to form aggregates under given environmentalconditions.

All solid particles experience short range excluded volume repulsions,which does not prevent agglomeration due to longer range attractiveforces such as Van der Waal's attractions. Particles may be physicallyseparated using longer range repulsive forces such as stericinteractions. Alternatively and/or additionally particles can beprevented from aggregating by manipulating electrostatic interactionsbetween the particles. For instance, dispersed particles may be coatedwith a steric material to prevent subsequent re-aggregation.Alternatively and/or additionally, the chemical conditions of theparticles in suspension may be modified (e.g. by changing pH, saltconcentration, etc. of the solvent system) to influence the interactionof particles (e.g. by modifying surface charge).

In various approaches, the one or more stabilizing agents 110 mayinclude any combination or single agent selected from a polymer, asurfactant, an acid, a base, an electrolyte, a polyelectrolyte and/or asalt. In preferred approaches the stabilizing agents 110 may include oneor more of: polyvinylpyrrolidone (PVP), polyethylene glycol (PEG),citric acid, polyacrylic acid, sodium polyacrylate, polyethyleneimine,and ammonium polymethacrylate.

In various approaches, the stabilizing agents may be present in thereactive ink formulation in an amount greater than 0 vol % and less thanabout 15%, preferably greater than 0 vol % and less than about 10%, andmore preferably greater than 0 vol % and less than about 1%.

In more embodiments, the reactive ink formulation may optionally and/oradditionally include one or more gelation agents. A gelation agent maybe added to controllably gel a stabilized ink formulation (e.g. asuspension) so that the formulation develops appropriate viscoelasticproperties and solid-like behavior while not under shear stress.Conversely, under shear stress, formulations including a gelation agentor agent(s) may advantageously become more liquid-like which allows easeof flow through a nozzle. After the formulation comprising the gelationagent exits the nozzle, it will solidify or re-gel to maintain itsshape, advantageously conferring additional structural support to thedeposited/extruded formulation.

In some embodiments, the particles themselves may be employed as thegelation agent, and the desired flow properties may be achieved byadding an additional component such as a polyelectrolyte to influencethe manner in which the particles physically interact, modifying therheological properties of the overall reactive ink compositionaccordingly.

In the foregoing manner, it is possible to tailor the flow propertiesand solidification behavior in order to obtain inks that readily flowthrough fine nozzles without clogging, yet are self-supporting upondeposition. For example, the rheology of nanoparticle inks may be tunedby varying the ratio of stabilizing agent to gelation agent, or byaltering the volumetric ratio of attractive to repulsive particles for abinary-order (or higher) system. The viscoelastic response can also betuned so that the presently described reactive inks rapidly “set” uponexiting the nozzle and maintain their shape, allowing for constructionof 3D architectures in a layer-by-layer fashion.

In still more approaches, the multifunctional reactive inks disclosedherein may include additional components, such as a humectant to drawmoisture into the ink and/or a graded volatility solvent system such asdescribed above. Adding a humectant may be particularly advantageous formultifunctional reactive inks utilizing aqueous solvents but having atendency to dry too quickly, causing the ink to clog the nozzle duringextrusion and/or negatively impacting the structural characteristics ofthe deposited ink.

Other additional components may include one or more adhesion and/orbrazing agents to assist in adhering layers of deposited reactive inkmaterial. For example, in one embodiment a multifunctional reactive inkmay include nickel and aluminum particles designed to carry aself-propagating and/or self-sustaining reaction to completion uponinitiation, in addition to silver nanoparticles designed to facilitatebetter adhesion of the resulting aluminum-nickel material to thesubstrate. Without wishing to be bound to any particular theory, theinventors propose generally that adding particles that can melt duringreaction and facilitate wetting the substrate will improve adhesion.Other techniques for improving adhesion include enhancing innerdiffusion of species and flow transport between the multifunctionalreactive ink and the substrate material.

FIG. 2 is a simplified schematic of a 3D printing apparatus 200 suitablefor use in printing multifunctional reactive ink as described herein,according to one embodiment.

As shown, the 3D printing apparatus 200 includes a three-dimensionalprinting apparatus 202 (white box coupled to a three-axis support), areservoir 204 and a nozzle 206 coupled to the printing apparatus 202,and further coupled to the reservoir 204 via one or more fluidicchannels 208.

In various embodiments, the positioning apparatus 202 is configured totranslate the nozzle 206 in at least one dimension relative to asubstrate 210. In FIG. 2, the positioning apparatus 202 is configured totranslate the nozzle 206 in three linear dimensions (x, y, z) relativeto the substrate 210. Thus, the system depicted in FIG. 2 couldtranslate the nozzle 206 throughout a three-dimensional Cartesiancoordinate space in proximity to the substrate 210, depositingmultifunctional reactive ink from the reservoir 204 via fluidicchannel(s) 208 according to a predetermined pattern to form a customthree-dimensional structure capable of carrying out a self-propagatingand/or self-sustaining reaction to completion upon initiation thereof.

In alternative embodiments, the positioning apparatus 202 may beconfigured to translate the nozzle 206 along rotational or radial axesin addition to linear axes. In still more embodiments, the positioningapparatus may be configured to translate the nozzle 206 along one or twoaxes (e.g. the x axis or x and y axes shown in FIG. 2) and the substrate210 may be configured to translate along one or more additional axes toaccomplish custom printing. For example, in one illustrative approachthe nozzle 206 may be able to translate in the y direction, while thesubstrate is mounted on a positioning apparatus 202 configured to movethe substrate in the x and z axes. In operation, the nozzle may beslowly drawn up as material is extruded onto the moving substrate tobuild the predetermined structure vertically, according to oneembodiment.

In still more embodiments, the positioning apparatus may be coupled tothe substrate 210 rather than the nozzle 206, which may be fixed. Inprinciple the operation of the apparatus is substantially similar, withthe positioning apparatus 202 translating the substrate 210 throughout athree-dimensional Cartesian coordinate space with reference to the fixedposition of the nozzle 206 according to a predetermined pattern to formthe desired three-dimensional structure.

Of course, as would be understood by one having ordinary skill in theart upon reading the present descriptions, multifunctional reactive inksdisclosed herein may be printed without the assistance of complexmachinery. For example, in one embodiment a reactive ink may be printedonto a substrate using a simple fluidic system, such as a systemcomprising a reservoir, a nozzle and a plunger (e.g. a syringe or caulkgun). This ability to print using minimal hardware makes the instantlydisclosed multifunctional reactive inks far more accessible andapplicable to custom applications. As no complex machinery is required,a user may simply direct the extrusion/deposition process by hand,enabling applications such as repair or modification of pre-existingstructures without the use of any tool other than the simple fluidicsystem.

For example, one illustrative application enabled by this user-drivenapplication process is to repair a tear in a piece of metal.Conventional 3D printing techniques would be ill-suited (if capable atall) for performing such tasks because the topology of the substrate, inthis case the tear, (as well as the “proper” topology of the metalbefore tearing) is unknown and/or difficult to infer or calculate. Ahuman user, however, could simply apply a multifunctional reactive inkby hand and initiate the corresponding reaction to effectively print arepaired part (albeit with less precision than a computer-driven methodwith precise knowledge of the substrate topology and desired topology).

Another illustrative use would be making repairs or modifications to amachine or component thereof in an extreme environment neither suitablefor conventional repair techniques nor 3D printing. An aqueousenvironment, such as an oceanic pipeline, offshore rig, naval vessel,etc. may present unique difficulties such as the damaged component beingsubmersed in an excellent heat-sink and the need to use dangerouselectrical instruments in an aqueous environment. Multifunctionalreactive inks could replace conventional hyperbaric welding toaccomplish undersea repair without introducing risk of electrocution bysimply printing the ink and initiating a reaction to heal the material.Similarly, welding-type activities could be carried out in anoxygen-free environment such as the vacuum of space because themultifunctional reactive ink may supply all necessary components of thecorresponding reaction, enabling on-site repair of orbiting equipment.

FIG. 6 is a flowchart of a method 600 for fabricating reactive inkcommensurate in scope with the presently described inventive concepts,according to one embodiment. The method 600 may be performed in anysuitable environment, including those shown in FIGS. 1-5, among others,in various approaches.

Method 600 includes operation 602, where a plurality of particles aredispersed in a solution to form a dispersion. The particles include atleast two types of particles to form an at-least binary-order reactivesystem, such as particles 106, 108 as shown in FIG. 1 and describedabove. The particles are dispersed in method 600 to disaggregateclustered particles in order to facilitate even distribution thereofthroughout the ultimate reactive ink formulation. The particles may bedispersed using any suitable technique, using mechanical and/or acousticforces such as shaking, stirring, vortexing, (ultra)sonication, etc. aswould be understood by one having ordinary skill in the art upon readingthe present descriptions.

Dispersed particles, if left alone, have a tendency to re-formaggregates after dispersion due to attraction from weak interactionssuch as hydrogen bonds and/or Van der Waal's forces. In order to retard,or preferably defeat, the aggregation process, method 600 also includesoperation 604, where one or more stabilizing agents are added to thedispersion. The stabilizing agents may be added in an amount sufficientto cause the dispersion to exhibit one or more rheological properties,e.g. viscosity, shear, storage and loss modulus, density, flowproperties, volume fraction of particles, etc.

In preferred embodiments, this even distribution enables more consistentextrusion (e.g. because rheological properties are substantiallyidentical for the entire formulation) and reaction propagation (e.g.because particles of each type are present throughout the entire inkformulation in a desired stoichiometric ratio and/or with a desiredphysical proximity to one another).

Further approaches may include additional and/or alternative operationsto formulate the multifunctional reactive inks disclosed herein. Forexample, in some approaches method 600 may additionally includeconcentrating the multifunctional reactive ink. Concentration operationssuitable for use in forming multifunctional reactive inks as discussedherein include, but are not limited to, evaporation-based techniques,sedimentation techniques, and separation techniques. For example, insome embodiments the multifunctional reactive ink formulation formed inoperations 602-604 may be incubated at a predetermined temperature (e.g.400 C) sufficiently low to avoid initiating any chemical reactionbetween the plurality of particles and sufficiently high to facilitatenear-complete (e.g. 99%) evaporation of the solvent.

Additionally and/or alternatively, concentration may include allowingthe dispersed particles to form a sediment on the bottom of a reservoir,and decanting/aspirating away the supernatant solvent.Sedimentation-based and separation-based concentration techniques may besupplemented by centrifugation, in some approaches.

Materials Repair

Referring now to FIGS. 3A-3B, we turn to describing an exemplaryembodiment of using multifunctional reactive inks as described herein torepair materials. In the illustrative scenario, a device includescomponent 300 comprising a substrate 302 having incurred physical damagein a region 304. Physical damage may include any type of damage,including tears, holes, alterations to chemical makeup of the substrate(e.g. due to reduction-oxidation reactions, radiation, etc.), physicaldistortion of the substrate, etc. as would be understood by one havingordinary skill in the art upon reading the present descriptions.

In order to effectively repair the substrate 302, the damaged region 304is at least partially filled with a multifunctional reactive inkaccording to any method described herein, or any equivalent thereof. Thereactive ink is then initiated, and the self-propagating and/orself-sustaining reaction proceeds to completion, resulting in thedamaged region 304 of substrate 302 being filled/repaired, as indicatedin FIG. 3B by repaired region 306.

Similarly, in other applications a reactive ink may be employed torepair a conductive component to restore conductivity thereto. Forexample, with reference again to FIGS. 3A-3B, region 304 may reside inthe path of a printed circuit, e.g. on a printed circuit board (PCB).Damage in region 304 may have broken the conductive path through thecircuit, and a reactive ink configured to form a conductive compositeupon reaction may be printed in the damaged region. After reaction, thedamaged region 304 may be filled in whole or in part by the composite306 formed by the reactive ink, and conductivity thereby restored to thecircuit.

Still more similar applications include using the reactive inks as atype of switch in an arming device. Continuing with the PCB exampleabove, a PCB arming component of a device may utilize a printed circuitcomprising unreacted reactive ink configured to form a conductivecomposite, and the PCB may further include some initiation device tocreate a spark, heat, etc. for initiating the reaction. After reactingthe multifunctional ink, the PCB comprises a conductive path forcarrying electricity, e.g. to a detonator.

In still more embodiments, repair may include strengthening thesubstrate material. For example, the reactive ink material be composedof perhaps more exotic materials than the part itself, the exoticmaterials conferring superior mechanical properties or betterperformance than the rest of the material itself so the repaired regionof the material is not actually the weakest portion thereof.

For instance, in one embodiment the repaired region may be titaniumdiboride formed by reacting a multifunctional reactive ink comprisingconstituents of titanium and boron, and the formulation may be used torepair or reinforce structural steel. The original part may not becomprised of titanium diboride because it was cost-prohibitive to use inde-novo fabrication. However, advantageously reactive ink printing ismore cost-effective because it is possible to direct and print thismaterial exactly where needed, restoring strength to some percentage ofthe original part's value (according to any standard technique ofmeasuring mechanical strength) and that may even be over 100 percent ofthe original value.

Reactive Additive Manufacturing

FIG. 7 depicts a flowchart of a method 700 for fabricating materialsusing reactive additive manufacturing, according to one embodiment. Themethod 700 may be performed in any suitable environment, such as thosedepicted in FIGS. 1-5, among others, in various approaches. Method 700includes operation 702, where a material is deposited on a substrate.Uniquely, the material includes a plurality of particles (e.g. particles106, 108 as shown in FIG. 1) configured to complete a self-propagatingand/or self-sustaining reaction upon initiation thereof, a solventsystem (e.g. solvent system 104 as shown in FIG. 1) and one or morestabilizing agents (e.g. stabilizing agents 110 as shown in FIG. 1).

The reactive ink utilized in method 700 may have any combination offeatures described above with regard to reactive inks within the scopeof the present disclosures, including composition, rheologicalproperties, reactive properties, etc., in various embodiments. Moreover,method 700 may include one or more additional and/or alternativeoperations, in several approaches.

For example, in one embodiment method 700 may further include initiatingthe self-propagating and/or self-sustaining reaction. As will beappreciated by those having ordinary skill in the art upon reading thepresent descriptions, initiation may be accomplished by any suitablemeans of imparting enough energy to initiate the reaction, includingapplying a spark, flame, or electrical potential, initiation by chemicalreaction, optical initiation, etc. as would be understood by one havingordinary skill in the art upon reading the present descriptions.Initiating the reaction may preferably result in a fully-functionalcomponent being formed, e.g. in one approach suitable for use inrepairing naval vessels the component may be water-tight and capable ofwithstanding a predetermined amount of pressure without experiencingstructural failure.

In many approaches, the reactive inks have physical characteristics ofbeing deposited by extrusion through a nozzle such as a micro-nozzle. Inpractice, the reactive ink may be deposited by applying pressurethereto, for example using air pressure or a linear displacementmechanism. Air pressure is a preferred method for starting and stoppingthe ink flow, while a linear displacement mechanism is preferred whenextruding reactive inks exhibiting time dependent rheology and/or timedependent viscosity. Of course, other extrusion techniques may beutilized without departing from the scope of the present disclosures.

In preferred approaches, the physical characteristics of being depositedby extrusion may include the deposited multifunctional reactive inkmaterial having a feature size not more than two orders of magnitudelarger than a diameter of the nozzle from which the ink was extruded.

In various approaches, multifunctional inks as described herein may bereactive during extrusion, upon deposition, and/or after an optionalcuring step such as a simple room-temperature evaporation or a thermalcuring to facilitate evaporation of solvent and/or additional materialssuch as binding agents, organics, stabilizing agents, gelation agents,etc. as would be understood by one having ordinary skill in the art.

In another instance, the multifunctional reactive ink is deposited as aseries of layers. The layers may be formed of the same multifunctionalreactive ink, or different multifunctional reactive ink formulations maybe layered sequentially, in various approaches.

In some embodiments, the resulting layered structure may be suppliedsufficient energy to initiate the self-propagating and/orself-sustaining reaction, which proceeds to completion to form amonolithic structure such as a cube or cylinder (such as shown in FIGS.4A-4B and described below). Alternatively, each layer may have itsreaction initiated upon extrusion/deposition, i.e. subsequent todepositing the layer and prior to depositing a subsequent additionallayer or layer(s).

In some embodiments, the reactive ink may be used primarily to supplyenergy to melt an adjacent layer. For example, a layer of silver isprinted, followed by a layer of the reactive ink. The reactive ink isthen ignited to supply a heating source to melt the silver layer. Thisprocess is repeated as many times as necessary until the desired part ismade.

FIGS. 4A-4B depict various embodiments of structures printed usingmultifunctional reactive inks in a manner consistent with thosedescribed above regarding FIG. 7. More specifically, FIG. 4A shows alayered structure 400 of one or more multifunctional reactive inksdeposited in a series of layers 402. Each layer 402 may include one ormore different reactive ink compositions as described herein, and upondeposition, each layer 402 may be initiated prior to depositing thesubsequent layer 402, or alternatively a subset (up to all) layers 402may be deposited and the corresponding reactions thereof initiated in asingle instance.

Whether reacting each layer individually or all at once, the resultingstructure 410 is shown in FIG. 4B as a composite monolith 412 of thereacted layers 402. Preferably, the resulting structure 410 issubstantially identical to the deposited multifunctional reactive inkwith respect to macro-scale (e.g. >0.5 mm) size and geometry.

FIG. 5 depicts another exemplary arrangement of printed multifunctionalreactive inks within the scope of the presently described inventiveembodiments. As shown in FIG. 5, the three-dimensional structure 500 isagain a multilayered structure as depicted in FIG. 4A, but includes acentral gap interior to layers 502, 504 and 506, respectively,resembling a bridge or archway when viewed from the perspective shown.Because the multifunctional reactive ink is self-supporting, thestructure 500 may be printed as-is and substantially retain itsconfiguration after drying/or and reaction. There is not a substantial“sagging” effect in the region above the void (i.e. in layers 506) dueto the unique structural characteristics of the presently describedinks.

In another embodiment, FIG. 5 represents a two dimensional structure 500such as a printed circuit of a PCB. For example, features 504 may beprinted from a reactive ink configured to form a relatively resistivematerial suited for use as a resistor in a circuit. Similarly, features506 may be printed from a reactive ink configured to form a materialsuitable for use in a capacitor of a circuit, and features 502 may beprinted from a reactive ink configured to form a highly conductivematerial suitable for use in a circuit. Upon completing the reaction,the PCB additionally includes a capacitor-to-resistor circuit element.Alternative configurations using various additional and/or othermaterials to form different types of circuit elements are also withinthe scope of this disclosure, as would be understood by skilled artisansupon reading the present descriptions.

In some approaches, printing multifunctional reactive inks may include afeedback mechanism to determine the success of printing the desiredfeatures (e.g. to measure distortion in three dimensions). One exemplaryapproach for providing such feedback is laser prolifometry, which may beutilized to scan and adjust the printing process to account fordeviations (e.g. by measuring stress, thermal gradients, etc.) from theintended structure and “fix” printing errors in near real-time.

Thermal/Chemical Work

In more embodiments, multifunctional reactive inks may be utilized toperform thermal and/or chemical work, imparting energy onto/into asubstrate upon which the ink is deposited upon initiating thecorresponding reaction the ink is designed to carry to completion.Exemplary applications of using multifunctional reactive inks to performthermal and/or chemical work include use as a heat source in a thermalbattery, to cut or separate materials, to etch, stamp or labelmaterials, to fuse materials, to initiate a reaction, etc. as would beunderstood by one having ordinary skill in the art upon reading thepresent descriptions.

For example, in one embodiment a multifunctional reactive ink may beprinted onto an aluminum substrate according to a predetermined patterndesigned to produce a desired configuration/structure in the aluminumupon initiating a reaction the multifunctional reactive ink is designedto carry to completion. Upon initiation, the ink imparts sufficientthermal energy to melt the aluminum substrate, effectively cutting thesubstrate and separating a portion thereof according to thepredetermined pattern. The portion may be removed from the remainingsubstrate and further processed or put directly to its intended use.

Additionally and/or alternatively, multifunctional reactive inks may bedesigned to perform sufficient thermal and/or chemical work to etch ormar a material for purposes of creating a label, stamp, or otheridentifying mark. The reactive ink may be printed in a predeterminedpattern, for example mimicking a logo, and upon reaction, may etch thesurface of the substrate, marking the substrate surface to depict thelogo.

In still more embodiments, multifunctional reactive inks may be used tofuse objects, e.g. in a manner akin to brazing or soldering. A substratesurface may be “cleaned” using, for example an acid, and subsequently amultifunctional reactive ink is printed onto the cleaned substratesurface. Upon completing the self-propagating and/or self-sustainingreaction the multifunctional reactive ink is designed to perform, thesubstrate is fused.

Additional Practical Applications

Embodiments of the present invention may be used in a wide variety ofapplications. For example, in addition to repairing existing materialsand fabricating new materials in an additive fashion, multifunctionalreactive inks may be utilized to impart desired properties and/orfunctionalities on various substrates. For example, a structure (such asa door panel of a military vehicle or panel of a satellite) isfabricated using conventional means. The structure is intended for usein applications which benefit from resistance to radiation, heat, and/orapplication of acute physical force. In order to confer theseproperties, a multifunctional reactive ink comprising precursormaterials for an appropriate ceramic or cermet material may be printedonto the structure, (or the structure may be dipped or otherwise coveredin in the multifunctional reactive ink, etc. as would be understood byone having ordinary skill in the art upon reading the presentdescriptions. A self-propagating and/or self-sustaining reaction is theninitiated to form a layer of the ceramic or cermet material on thestructure, conferring the corresponding radiation resistance, thermalinsulation, and/or physical resistance of the ceramic/cermet material tothe resulting structure.

It should be noted that any of the presently described materials andtechniques for use and/or manufacture thereof may be utilized in anycombination or permutation. While certain techniques have been set forthunder headings and with reference to particular applications, one havingordinary skill in the art reading the present disclosure wouldappreciate that each technique, and even the sub-techniques thereof,could be utilized broadly in any suitable application. Accordingly, theforegoing descriptions are not to be considered limiting on the mannerof manufacturing or using the multifunctional reactive inks describedherein.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. A method, comprising: dispersing a plurality ofparticles in a solution to form a dispersion; and adding a stabilizingagent to the dispersion in an amount sufficient to cause the dispersionto exhibit one or more predetermined rheological properties, wherein theone or more predetermined rheological properties include the dispersionbeing structurally self-supporting during deposition thereof onto asubstrate and prior to initiation of a self-propagating and/orself-sustaining reaction; and wherein the particles in the dispersionare configured to complete a self-propagating and/or self-sustainingreaction upon initiation thereof.
 2. The method as recited in claim 1,wherein the particles comprise a binary or higher order reactive system.3. The method as recited in claim 1, wherein the particles comprise fromabout 30 vol % to about 80 vol % of the dispersion.
 4. The method asrecited in claim 1, wherein the dispersion comprises the particlesdispersed throughout a liquid metal matrix.
 5. The method as recited inclaim 1, wherein the particles are characterized by a core-shellconfiguration.
 6. The method as recited in claim 1, wherein theparticles are characterized by an average diameter in a range from about0.01 microns to about 100 microns.
 7. The method as recited in claim 1,wherein the stabilizing agent includes one or more components selectedfrom the group consisting of: at least one polymer, at least onesurfactant, at least one acid, at least one base, at least oneelectrolyte and/or at least one polyelectrolyte, and at least one salt.8. The method as recited in claim 7, wherein the at least one polymer isselected from the group consisting of: polyvinylpyrrolidone (PVP),polyethylene glycol (PEG), polyacrylic acid, sodium polyacrylate,polyethyleneimine, and ammonium polymethacrylate.
 9. The method asrecited in claim 1, wherein the one or more predetermined rheologicalproperties are selected from the group consisting of: viscosity, shear,storage, loss modulus, density, flow properties, and volume fraction ofthe particles.
 10. The method as recited in claim 1, wherein thedispersing comprises one or more operations selected from the groupconsisting of: shaking, stirring, vortexing, and sonicating.
 11. Themethod as recited in claim 1, further comprising heating the dispersionto remove a solvent therefrom without initiating any chemical reactionbetween the plurality of particles.
 12. The method as recited in claim1, further comprising adding at least one additional component to thedispersion, wherein the at least one additional component is selectedfrom the group consisting of: a humectant, a graded volatility solventsystem, a brazing agent, a gelation agent, and an adhesion agent. 13.The method as recited in claim 1, wherein the self-propagating and/orself-sustaining reaction generates heat, and wherein the heat generatedby the self-propagating and/or self-sustaining reaction at leastpartially melts at least one adjacent layer comprising a seconddispersion.
 14. The method as recited in claim 1, wherein the particlesin the dispersion are configured so that the self-propagating and/orself-sustaining reaction comprises a thermite and/or an intermetallicreaction.
 15. The method as recited in claim 1, further comprisingdepositing one or more layers of the dispersion onto a substrate. 16.The method as recited in claim 15, wherein the particles in thedispersion are configured so that the self-propagating and/orself-sustaining reaction renders at least one surface of the substrateonto which the dispersion is deposited conductive.
 17. The method asrecited in claim 15, further comprising cleaning a deposition surface ofthe substrate with acid prior to depositing the one or more layers ofthe dispersion.
 18. The method as recited in claim 15, furthercomprising depositing one or more additional layers of a seconddispersion to form a structure comprising alternating layers of thedispersion and the second dispersion, and wherein the layers of thesecond dispersion comprise a non-energetic material.
 19. The method asrecited in claim 18, further comprising initiating the self-propagatingand/or self-sustaining reaction in each layer of the dispersion; whereineach self-propagating and/or self-sustaining reaction generates heat,and wherein the heat generated by each self-propagating and/orself-sustaining reaction at least partially melts at least one adjacentlayer comprising the second dispersion.
 20. The method as recited inclaim 15, further comprising initiating the self-propagating and/orself-sustaining reaction in each layer subsequent to deposition thereofand prior to depositing a subsequent additional layer.